Wheeled vehicles are usually steered by rotating wheels about their vertical axis (double-pivot or Ackermann steering). In order to avoid the associated additional expenditure with respect to steering gears and bearings for the steered wheels having free axles and in order to permit a significantly greater degree of mobility as a result of a smaller steering radius, a technique referred to as “wheel-based steering” is sometimes used in wheeled vehicles. For example, this technique is often used in the construction industry or in military wheeled vehicles. In wheel-based steering, the vehicle's wheels on the inside of the bend must be braked during cornering. In the construction context, such vehicles are usually used only for slow velocities since at relatively high velocities higher braking power is necessary for steering.
Efficient drive systems for high speed vehicles with wheel-based steering often conserve the braking power produced by the wheels on the inside of the steering curve and transfer that power to the wheels on the outside of the steering curve. The term regenerative steering is often used to describe this type of technology.
However, when using this technique on vehicles with separate electrical drives for each drive side or for each drive (crawler) wheel, the performance of the electric motors must be configured not only to accommodate the power of the prime power generator (for example diesel engine) but also based to accommodate the regenerative power. This requirement leads to significantly over designed electric motors and complex cable systems to handle the correspondingly large electrical currents.
DE 198 50 606 discloses such an arrangement for use in crawler vehicles. An internal combustion engine driving a generator generates electrical power for driving the vehicle via electric drive motors. Regenerative steering (i.e., electrical power transmission from drive motors on the inside of the bend to drive motors on the outside of the bend) is also disclosed. U.S. Pat. No. 1,997,974 discloses a wheeled vehicle with a wheel hub motor. In this reference, the motors are relocated to the empty space in the interior of the wheels, which is otherwise unused, so that there is more space available in the interior of the vehicle.
DE 37 28 171 describes an electromechanical drive system for full track vehicles. In the simplest case, this drive system is composed of an electric drive motor which drives both sides of the vehicle in the same direction by means of a central shaft, and an electric steering motor which drives a zero shaft whose rotation speed has a positive effect on one side and a negative effect on the other. Steering differentials on the left and right add the rotational speeds of the two motors and pass on the sum to the crawler wheels. This solution provides the advantage that the electromechanical steering can transmit a multiple of the rated power of the steering motor as what is referred to as “regenerative power” from the drive side on the inside of the bend to the drive side on the outside of the bend. As a result of this electromechanical transfer of power, the regenerative component flows via the mechanical gear mechanism arrangement and not via the electric motors so that they can be configured in accordance with the primary power of the vehicle. However, a disadvantage in comparison to drives with wheel hub motors is that increased installation space is required in the interior of the vehicle, and which wastes space and vehicle capacity.